The present invention pertains to devices for gaining access to security containers, and more particularly to devices that can be used to cut a lock bolt of a security container.
Various types of security containers are used for such purposes as storing confidential or sensitive documents, valuables, and the like. Typical of such security containers are secure filing cabinets having combination locks to prevent unauthorized access. Occasionally, it becomes necessary to gain access to such containers by use of force, such as by drilling the lock bolt, usually when the combination has been lost or when the lock mechanism has malfunctioned.
The use of a power drill to gain access to a locked security container is known in the art. U.S. Pat. No. 5,984,594 describes an apparatus and method for drilling a small hole near the lock mechanism to allow a locksmith to observe the inner workings of the lock. Drilling into the lock itself is generally undesirable due to the considerable expense involved in repairing or replacing the lock. Therefore, it is preferable to gain access to and cut the lock bolts of such a container. Typically, a carbide-tipped hole-saw is used to cut through a front surface of the container, such as the front surface of a drawer, and then through the lock bolts behind the front surface. Often these lock bolts are formed from one-inch diameter cylindrical rods of hardened steel. Because the lock bolts are generally supported only near their ends, they tend to bind against a hole-saw under the considerable pressure required to cut through them. This binding generates excessive heat and tool chatter which can damage the carbide tips of a hole-saw and makes cutting the bolts difficult.
Referring to FIGS. 1 and 2, the prior art method of cutting a lock bolt will now be described. FIG. 1 shows a security container 10, in the form of a secure filing cabinet, with access drawer 12 that can be secured in a closed position by a pair of lock bolts 14 and 16. In a closed and locked state, ends 18 and 20 of lock bolts 14 and 16 engage apertures 19 and 21 in container 10 that are adapted to receive the lock bolts and prevent opening of the drawer. A combination dial 22 is used to actuate a locking mechanism 24 to provide an unlocked state, whereby lock bolts 14 and 16 may be retracted from the container apertures by actuation of a lever 26, or alternatively by rotation of the dial 22.
In the event that lock mechanism 24 has malfunctioned or the combination has been lost, entry into container 10 is often obtained by cutting lock bolts 14 and 16 using a carbide-tipped hole saw 28. Typically, the hole-saw 28 is advanced through a front panel 29 of drawer 12, creating panel hole 57, and subsequently through lock bolt 14 by using a drill rig 30. A typical drill rig used for such purposes is the MAG457100 Bullet Rig and L2021 Tower Assembly, available from Lockmasters, Inc. A drill plate 32 is fastened to drawer panel 29 in a location near lock bolt 14 using self-tapping screws 34. Stand-offs 36 support a flanged mounting plate 38 secured by cap screws 40. A first tube 42 has internal threads (not shown) and is slidably attached to the flanged mounting plate 38 by a quick-release locking collar 44. Detents 46 on the first tube 42 engage the locking collar 44 to lock first tube 42 in place at various positions along the axial length of the tube.
A second tube 48 is fitted inside first tube 42 and has external threads (not shown) which operatively engage the internal threads of the first tube 42 such that the second tube can be advanced or retracted axially along first tube 42 by manual operation of a wheel 50 fixed to the end of second tube 48. A freely rotating spindle 52 is positioned in the bore of second tube 48 and has a tool chuck 54 fixed to one end for holding hole saw 28. The spindle 52 is fixed axially relative to the second tube 48 by thrust bearings (not shown) so that the spindle 52 moves with the second tube 48 as wheel 50 is manipulated. A driven end 56 of spindle 52 is adapted to receive a driver whereby spindle 52 may be rotated using a power drill (not shown).
According to the prior art method of cutting lock bolt 14, drill plate 32 is attached to drawer panel 29 generally near lock bolt 14 and drill rig 30 is secured to drill plate 32. Locking collar 44 is manipulated to allow first tube 42 to be adjusted such that hole-saw 28 is adjacent the surface of the drawer panel 29. A power drill with an appropriate driver is fitted to the driven end 56 of spindle 52 and the drill is energized to rotate the spindle 52 and hole-saw 28 while being advanced through the surface of drawer panel 29 and subsequently through lock bolt 14 by hand manipulation of wheel 50. A typical security container utilizes at least two lock bolts, operating in tandem, thus the prior art method stated above must generally be repeated on the second lock bolt 16 before access to the drawer can be gained.
FIG. 2 shows a partial section view of the prior art cutting method of FIG. 1 taken along line 2xe2x80x942. Hole-saw 28 has penetrated the surface of drawer panel 29 and has advanced part way through lock bolt 14. As depicted in FIG. 2, lock bolt 14 is substantially unsupported along its length and the cutting force applied by hole-saw 28 causes lock bolt 14 to bend in a direction away from the hole-saw 28. The bending of lock bolt 14 in turn causes ends 58 of groove 60, cut into lock bolt 14, to pinch against hole-saw 28, binding the hole-saw from rotation and damaging the carbide tips.
Accordingly, there is a need for an apparatus and methods for drilling through the lock bolt of a security container without the typical binding action which creates the various problems discussed above.
The present invention provides a method and apparatus for supporting a lock bolt of a security container while the lock bolt is being cut with a hole-saw to gain access to the container. The invention provides various advantages over previous methods and apparatus for cutting such lock bolts by constraining the lock bolt from bending and binding against the cutter. For example, the present invention reduces heat generation and tool chatter. The invention thus provides more efficient cutting and extends the service life of the cutter.
In one aspect of the present invention, a lock bolt support member has an engagement portion shaped to engage the surface of a lock bolt for a security container. The engagement portion of the support member may be inserted through an access hole that has been formed in a surface of the security container, near the lock bolt. A connecting portion of the support member remains outside the security container and mates with a locking mechanism such that the support member may be clamped between the lock bolt and the surface of the security container, thereby preventing the lock bolt from moving while it is being cut.
In another aspect of the invention, the engagement portion of the lock bolt support member is generally hook-shaped.
In another aspect of the invention, the connecting portion of the lock bolt support member includes screw threads. Accordingly the locking mechanism includes a first nut with screw threads that operatively engage the threads of the connecting portion. The locking mechanism thus can be adjusted with respect to the connecting portion so that the bolt support member can be clamped against the surface of the security container.
In yet another aspect of the invention, the locking mechanism includes a second nut with screw threads that operatively engage the threads on the connecting portion of the bolt support member such that the first nut is tightened to secure the lock bolt support member in position relative to the lock bolt and the second nut is tightened to retain the first nut from loosening.
In a further aspect of the invention, the first and second nuts of the locking mechanism comprise knobs that can be manually manipulated.
In yet another aspect of the invention, a method for cutting a lock bolt concealed behind a panel of a security container includes forming a hole in the panel near the lock bolt, inserting a lock bolt support member through the hole, supporting at least one side of the lock bolt with the lock bolt support member, cutting the lock bolt with a cutting tool that is forced against the lock bolt, and inhibiting movement of the lock bolt in a direction away from the cutter using the lock bolt support member while the lock bolt is being cut.
These and other advantages, objectives and features of the invention will become more readily apparent to those of ordinary skill upon review of the following detailed description of an illustrative embodiment of the invention.